Multiple sclerosis (“MS”) is a disease which presents as recurrent attacks of focal or multifocal neurologic dysfunction. Its symptoms are multi-faceted and indefinite and include (but are not limited to) impaired vision, nystagmus, an inability to speak clearly, a decreased perception of vibration and position sense, intention tremor, muscular incoordination, limb weakness or paralysis, spasticity, and bladder problems. Harrison's Principles of Internal Medicine, p. 1995-2000 (11th ed. 1987).
The economic sequelae of MS are substantial. A cost of illness (COI) study conducted by Bourdette et al. retrospectively examined costs to the US Veterans Affairs (VA) for the treatment of 165 patients with MS over a 3-year period. Bourdette, D N, et al. Health Care Costs Of Veterans With Multiple Sclerosis: Implications For The Rehabilitation of MS. Arch Phys Med Rehabil, 74, pp. 26-31 (1993). Drug costs were not included in the study. The average cost to the VA associated with these patients was estimated at $35,000 per year.
Homes et al. conducted a prevalence-based COI study, surveying 672 members of the Multiple Sclerosis Society in the UK. Holmes, B A, et al. Br. J. Med Econ, 8, pp. 181-93. (1995). This study reported an annual burden, associated with medical cost and lost wages from MS, estimated at £1.2 billion for 1994. The state carried the largest burden with the principal cost drivers being state benefits (23.9% of total costs). National Health Service costs (12.8%) and lost tax revenue (12.3%). Drug costs were assumed to be nonsignificant and, therefore, were not included in the study. The burden of caring for patients with MS fell more heavily on hospitals and nursing homes, over general practitioners (GPs). The burden on the individual approximated that on the state, with 33% of total costs resulting from lost earnings (including caregiver and patient), and 11.7% attributable to private expenses. The remaining 6.3% of the total burden was borne by industry.
In order to establish a definite diagnosis of MS, accepted practice mandates that at least two episodes of neurological deficit must occur along with objective clinical signs of lesions at more than one site within the central nervous system. One problem with such a diagnostic method is that a period of ten to twenty years may pass between episodes of neurological deficit.
Another problem is that the symptoms of MS are so indefinite that it may be confused with several other conditions. It is therefore important during the differential diagnosis of the patient to exclude conditions having similar symptoms which can be effectively treated. For example a patient may be suffering from side-effects of various prescription drugs (e.g. phenytoin which can cause nystagmus, vertigo and muscle weakness), pernicious anemia, or various infections. Usually such conditions can be effectively treated. Therefore, a need exists for diagnostic methods for the early detection of pathological processes consistent with a diagnosis of demyelinating disease including, in one example, MS.